Mechanism for controlling cut-off valves



v(No-lvrod-el.)

J. WHBBLOCK. MEGHANISM :POE GONTROLLING GUT-OPF VALVES.

Patented 001;. 29,1889.

. ."UNITED.4 STATES PATENT OFFICE.

JEROME WHEELOCK, OF WORCESTER, MASSACHUSETTSl MECIdANlSM AFORCO-NTROLLING CUT-OFF VALVES.

SPECIFICATION forming part of Letters Patent No. 413,696, dated October29, 1889.

I Application filed March 23, 1889. Serial No. 304,463. (No model.)

` To all whom, it may concern:

Be it known that I, JEROME WHEELOCK, a

citizen of the United States, residing at in Mechanism for ControllingCut-OIT Valves' in Engines, of which the following, in connection withthe accompanying drawings, is a specification sufficiently clear anddescriptive to enable those skilled in the art to which my inventionbelongs to make and use the saine. My invention relates-to automaticcut-off engines in which the cut-off valve is operated by means of thelatch block'and link connected to the arm of the exhaust-valve andadapt-ed to be disengaged, from said latchblock by a trip-cam operatedby the governor, all of which are well-known and have been fullydescribed in Letters Patent No.144,174, granted to me on October28,1873; and my invention consists in the improved system of levers andconnections by which the trip-cams are operated, as will be fullydescribed, and particularly pointed out in the claims.

Heretofore it has been a serious objection that the link could not bedisengaged from the latch-block attached to the arm of the cutoff valve,except at certain individual points of lits forward travel, on accountof the stationary condition on part of. t-he trip-cam during the fullstroke of the piston, when the engine is running at' comparativelyuniform speed-for instance, when the engine is running so slow thatthegovernor does not cause the trip-cams to liberate the cut-off valve,even at the farthest point of travel in the valves. Steam is thenadmitted into the cylinder for almost the full stroke of the piston, andif any load on the engine should be suddenly removed the cut-oif valvecannot be tripped during the return travel of the exhaust-valve crank,and the acceleration in speed would necessarily be so as to disturb theeven movement of the fly-wheel, which in some casesis very detrimentalto the machines which are driven by the engine-for example, to dynamosfor electric lighting, which require a uniform and unvarying speed. Thisobjection I overcome by the improved system of operating the trip-camsforming the subject of this application, and which is fully shown in thdrawings, in which- Figure 1 represents a side view of an automaticcut-oif engine generally known as the Wheelock engine and embodying myim-. provenlents. Figs. 2 to li, inclusive, are diagrains showing thepositions which the tripcams assume under different conditions ineccentric and governor.

Similar letters refer to similar parts.

In the drawings, A is the cylinder, into the steam-chest a of whichsteam is admitted by the throttle B and then passes through the cut-offvalves C C into the cylinder.

D are the exhaust-valves, allowing the used steam to pass out ofthecylinder and through the exhaust-pipes b.

As the construction is well known, aswell as the operation of thecut-off valve by the arm of the exhaust-valve, I do not deem itnecessary to describe the same fully, as the parts pertaining to thevalve-operating mechanism are substantially the same in all cases. E isthe engine-bed, supporting at its forward end the crank-shaft F,carrying the eccentric G, which, through the rocker H,im

parts an oscillating motion to the arms c of the main valves.

To the arm c is pivoted the link d, havin gl a bolt d', on which slidesa latch-block, which is secured to the arm e of the cut-off valve.

tric-strap Gis attached the link j, the other end ofwhich is secured tothe lever I, which 9 5 is pivoted at 7e to the engine-bed E, and therear end of which is connected through the link Z with the bell-cranklever J. K is the engine-governor, the balls of which cause the rise orfall of therod m., which adjustably roo supports the cross-head n,sliding in ways 0, which are secured to or made integral with the bottomplate o of the oil-reservoir of the governor. The bell-crank lever J ispivoted at p to the cross-head n., and its lower end is in directconnection with' the lever h above mentioned. In Fig. 1 the governor isrepresented in its lowest position, and the piston may thus obtain fullsteam from the oommencement of the stroke until the cut-off valve istripped, which heretofore could only be accomplished during the forwardmovement of the arm attached to the exhaustvalve. This would allow fullsteam for the piston for fully three-quarters of the stroke, and if theengine should not require that amount of steam a sudden start on part ofthe piston would be the result, and the steam could not be shut off onaccount of the arm of the cut-oft' valve being connected to the vslow-moving arm of the exhaust-valve.

By my improved system, as above described, I positively disengage thearm of the cut-olf valve at any point not exceeding three-fourths of thestroke, allowing the steam to expand and carry the piston to the end ofits stroke.

The operation is as follows: rlhe rotation of the shaft F impartsavibrating motion to the lever I, which in turn operates the bell-cranklever J, thereby causing a rocking motion on the part of the trip-camlevers 7L 7L', the amount of which is the same always, but the locationof which is regulated or controlled by the governor K, as may readily beseen by referring to Figs. 3 and 4 of the drawings,in which theeccentric is in the same position in both instances, while thecross-head carrying the bellcrank leverJ is in its highest position inFig.

3 and in its lowest position in Fig. 4. The amount of travel on part ofsaid bell-crank lever J, as indicated by the dotted lines s 3, isthe-same; but the location of such movelnent is forward in Fig. 4, sothat the tripcams f f', upon the slightest action on part of thegovernor, may release the cut-olf valve, even during the return travelof the exhaustvalve crank. In Fig. 3 the conditions are rcversed,inasmuch as the travel of the tripcams f f' is such as to prevent anyengagement of link andthe arm of the cut-off valve, so that the engineis at all times under full control of the governor, and the cut-olfvalve may be tripped at any point of the piston travel uptothree-quarters of the stroke. lt will thus be seen that during eachrevolution of the crank-shaft the trip-cams travel once back and forth,and will consequently disengage the link from the arm of the cut-offvalve during either forward or return movement of the exhaust-valvecrank and at any point where the cams will encounter said link, thelatter condition depending solely upon the position of thegovernor-balls.

Having fully described and explained my invention and its operation,what I claim new, and desire to secure by Letters Patent,

l. In a valve-gear for controlling the cut-olf valves of steam-engines,one or more tripcams which complete one forward and backward movementduring one revolution of the crank-shaft, means for operating the cams,and a governor for controlling the path of -travel of said cams,substantially as and for the purpose set forth.

2. In a valve-gear for controlling the cut-off valves of engines, thecombination of one or more trip-cams making a complete forward andbackward movement during one revolution of the crank shaft, with agovernor whereby the path of such movement is controlled, substantiallyas and for the purpose set forth.

3. In a valve-gear for controlling the cut-olf valves of engines, thecombination of one or more trip-cams with means, substantially asdescribed, for imparting to the trip-cams a complete forward andbackward movement during one revolution of the crank-shaft, and amovable fulcrum controlled by the governor for controlling the path oftravel of said cams, as and for the purpose set forth.

4. In a valve-gear for controlling the cut-off valves of engines, thecombination of one or more trip-cams, an eccentric for imparting to thesame a complete forward and backward movement during one revolution ofthe crankshaft, and a governor whereby the path of such movement iscontrolled, substantially as and for the purpose specified.

JEROME WHEELOCK. Vitnesses:

CHAs. F. SCHMELZ, IRvING H. FAY.

